The present invention relates to a new and distinct cultivar of Hydrangea macrophylla, a member of the Hydrangeaceae family, hereinafter referred to as ‘HYMMAD III’. This cultivar is grown primarily as an ornamental for landscape use and for use as a potted plant, fresh cut and dried flowers. The cultivar originated from open-pollination of Hydrangea macrophylla ‘Veitchii’ (non-patented), the pollen donor being unknown. It was selected at the University of Georgia, Athens, Ga. in 2001, from the progeny seedlings of this open pollination by continued evaluation for white lacecap flowers that mature to light pink or blue in the absence or presence of aluminum (Al), respectively, increased resistance to mildew, and improved habit, leaf, and stem characteristics.
‘HYMMAD III’ is distinguished from its female parent ‘Veitchii’ by its pure white, larger lacecap inflorescence that turns light pink or blue in the absence or presence, respectively, of Al. The sepals always open white and latently respond to Al. ‘HYMMAD III’ has lustrous dark green leaves, up to 26 cm long, much larger than ‘Veitchii’ (16 cm). ‘HYMMAD III’, like ‘Veitchii’, is highly mildew and Cercospora resistant, but it grows faster, has stronger stems, and larger, showier inflorescences. The flattened lacecap inflorescence averages 12 to 15 cm in diameter, about 25% larger than those of ‘Veitchii’.
‘HYMMAD III’ is distinguished from lacecaps such as ‘White Wave’ (unpatented) and ‘Lanarth White’ (unpatented) by its larger inflorescence, its larger and darker green leaves and its high resistance to mildew.